Thin Layer Peach Drying in Solar Tunnel Drier

This study presents performance of the solar tunnel dryer for drying of peach samples. The solar tunnel dryer consists of a flat plate solar collector, a drying tunnel, a solar cell module and a small axial fan. It has been constructed at the Department of Agricultural Machinery and Technologies Engineering at Isparta University of Applied Sciences. During the drying process, solar irradiation, drying air temperature, relative humidity, and air velocity were measured constantly in different parts of the dryer. At same time, mass loss of the peach samples was measured during the drying period at one-hour interval. In this study, the color measurements fresh and dried products were determined at the beginning and end of experiment. The fresh peach samples were sorted, graded, washed by tap water and then sliced manually as half-moon without peeling before pretreatment. Sun drying behavior of sliced peach samples pretreated with 1% sodium metabisulfit, 1% ascorbic acid and non-pretreated was investigated. The drying characteristic curves were evaluated against ten mathematical models. Results showed that the Midilli et al. model was found to be the best descriptive model for solar tunnel drying of thin layer peach.